The invention relates to a floating structure that can be moored to the seabed via anchor lines, at least one of the anchor lines comprising damping means for damping movements of the floating structure.
From U.S. Pat. No. 5,222,453 a marine structure is known, such as a semi-submersible drilling and production platform, which comprises anchor lines provided with clump weights or water-resistance elements to increase the dynamic mass of the anchor lines and to reduce the movements of the floating structure. Under varying loads on the anchor lines, the water resistance elements are displaced transversely to the length direction of the anchor lines. The water-resistance elements may comprise hollow spheres attached to the anchor lines, a plurality of radial fins or a radial slab. The water resistance elements damp movements of the anchor lines perpendicular to their length direction.
For anchoring floating structures in deep water, the anchor lines have considerable lengths, such as 1000 m or more. The anchor lines can in that case no longer be comprised of catenary chains, as the weight of such chains would become too large, and could, especially when the floating structure is a relatively small sized mooring buoy, submerge the floating structure. Catenary chains, used in shallow waters, have a damping effect on the movements of the floating structure. When anchor lines other than catenary chains are used, additional damping means must be provided in order to obtain a stable dynamic behaviour of the anchored structure. Radial fins or slabs such as known from the above prior art reference are not suitable for providing such a damping force when used in deep water.